Related papers: On the Composition of GRBs' Collapsar Jets
Jets in long-duration $\gamma$-ray bursts (GRBs) have to drill through the collapsing star in order to break out of it and produce the $\gamma$-ray signal while the central engine is still active. If the breakout time is shorter for more…
According the Collapsar model long gamma-ray bursts (LGRBs) involve relativistic jets that puncture the envelope of a collapsing star, and produced the \gamma-rays after they break out. This model provides a theoretical framework for the…
The plateau in the duration distribution of long Gamma-Ray Bursts (LGRBs) provides a direct observational evidence for the Collapsar model. The plateau reflects the fact that the observed duration satisfies: $T_{90} = t_{e}-t_{b}$ where…
Long Gamma Ray Bursts (lGRBs) are associated with jets in Type Ic broadline supernovae. The Collapsar model provides a theoretical framework for the jet formation from the core collapse of a massive star in such supernovae. The GRB can only…
The collapsar model explains the association of long duration gamma-Ray Bursts (GRBs) with stellar collapse. It involves a relativistic jet that forms at the core of a collapsing massive star. The jet penetrates the stellar envelope and the…
The Collapsar model provides a theoretical framework for the well known association between long gamma-ray bursts (GRBs) and collapsing massive stars. A bipolar relativistic jet, launched at the core of a collapsing star, drills its way…
The duration of the prompt emission of long gamma-ray bursts is generally considered to be fairly similar to the duration of the activity of the engine in the center of the progenitor star. Here, we investigate the relation between the…
We investigate by two-dimensional axisymmetric relativistic hydrodynamical simulations (1) jet propagations through an envelope of a rapidly rotating and collapsing massive star, which is supposed to be a progenitor of long duration gamma…
Aiming to study GRB engine duration, we present numerical simulations to investigate collapsar jets. We consider typical explosion energy ($10^{52}$ erg) but different engine durations, in the widest domain to date from 0.1 to 100 s. We…
We present our numerical results of two-dimensional hydrodynamic (HD) simulations and magnetohydrodynamic (MHD) simulations of the collapse of rotating massive stars in light of the collapsar model of gamma-ray bursts (GRBs). Pushed by…
We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle…
Gamma-ray burst light curves are characterized by marked variability, each showing unique properties. The origin of such variability, at least for a fraction of long GRBs, may be the result of an unsteady central engine. It is thus…
We study the long-term evolution of relativistic jets in collapsars and examine the effects of viewing angle on the subsequent gamma ray bursts. We carry out a series of high-resolution simulations of a jet propagating through a stellar…
Long-duration, spectrally-soft Gamma-Ray Bursts (GRBs) are associated with Type Ic Core Collapse (CC) Supernovae (SNe), and thus arise from the death of massive stars. In the collapsar model, the jet launched by the central engine must bore…
Growing observational evidence supports the proposition that gamma-ray bursts (GRBs) are powered by relativistic jets from massive helium stars whose cores have collapsed to black holes and an accretion disk (collapsars). We model the…
The prompt emission of gamma-ray bursts (GRBs) is characterized by rapid variabilities, which may be a direct reflection of the unsteady central engine. We perform a series of axisymmetric 2.5-dimensional simulations to study the…
Strong variability is a common characteristic of the prompt emission of gamma-ray bursts (GRB). This observed variability is widely attributed to an intermittency of the central engine, through formation of strong internal shocks in the…
In the collapsar scenario, gamma ray bursts are caused by relativistic jets expelled along the rotation axis of a collapsing stellar core. We discuss how the structure and time-dependence of such jets depends on the stellar envelope and…
Leading models for the "central engine" of long, soft gamma-ray bursts (GRBs) are briefly reviewed with emphasis on the collapsar model. Growing evidence supports the hypothesis that GRBs are a supernova-like phenomenon occurring in star…
We demonstrate that the steep decay and long plateau in the early phases of gamma ray burst (GRB) X-ray afterglows are naturally produced in the collapsar model, by a means ultimately related to the dynamics of relativistic jet propagation…